Protective gas masks or face masks are well known in the art. The masks provide breathing capabilities while protecting the mask user from noxious gases, smoke, etc. However, people wearing the masks often have a need to communicate with one another, particularly during emergency situations. Accordingly, several voice transmission or communication systems have been developed for this purpose.
For example, Lewis U.S. Pat. No. 3,180,333, discloses a gas mask communication system including a generally U-shaped holder connected to the mask. Preferably, the holder includes the amplification speaker in one end portion and the batteries for operating the speaker system in another end portion. The batteries and amplification system are connected in circuit with a microphone inside the mask adjacent the user's mouth. Additional or parallel speakers can be plugged into the Lewis mask communication system including, for example, a speaker attached to the belt of the wearer.
Ingels U.S. Pat. No. 4,508,936, Bloom U.S. Pat. No. 2,953,129, and Duncan U.S. Pat. No. 2,950,360, disclose face mask communication systems having a microphone carried in the face mask and an amplifier or speaker externally coupled to the face mask for support elsewhere, such as around the waist of the user.
The above-identified voice transmission and communication systems however, can have certain disadvantages. For example, the attachment of the amplifier or speaker to the waist can add weight and bulk to the unit and can partially limit the mobility of the wearer. Further, the direction of the amplifier or speaker on the waist does not necessarily follow the direction of the person's head. In other words, as the person turns their head to talk, the direction of the amplifier or speaker on the waist does not necessarily follow the person's head if the body does not simultaneously turn. By having the face and speaker potentially as much as 90.degree. apart in direction, the efficiency and effectiveness of these communication systems can be diminished.
Additionally, during installation (or removal and/or replacement), of some of these systems, the communication system must penetrate and structurally alter the mask in order to reproduce the user's voice. Penetrating and altering the mask however, can raise safety issues, requires additional assembly, and can make it difficult to remove and/or replace the voice transmission system, particularly during emergency situations.